Hydrogen may be used as a fuel source for fuel cells joined together to form a fuel cell stack. In the fuel cell stack, hydrogen is presented on the anode side whereas air is presented on the cathode side. The fuel cell stack generates electrical current in response to the electrochemical conversion of hydrogen and oxygen into water, which may then be used to drive various devices onboard the vehicle in addition to the vehicle itself.
One approach detecting hydrogen leaks on the anode side of the fuel cell stack is based on dropping vehicle power requests without supplementing power to the vehicle in order to perform the anode leak test (ALT). For example, U.S. Pat. No. 8,524,405 discloses conducting an anode leak test during a vehicle shutdown process when the power requested by the vehicle is already undergoing power reduction. As another example, DE 102009008654 or U.S. Pat. No. 7,942,035 conducts a leak test in a fuel cell vehicle only when a zero-load requirement is satisfied. In still another example, U.S. Pat. No. 8,349,509 discloses performing an anode leak test at vehicle startup and intermittently during operation, but fails to supplement the electrical power during test performance.
The inventors herein have recognized the above issues as well as that lacking an alternative energy source, anode leak tests may be limited to performance at low fuel cell powers, and performed during vehicle idle conditions. As such, infrequent checking for hydrogen leaks may occur in the anode of the fuel cell stack.
In one example, a method is provided for performing an anode leak test during vehicle operation, for example, when the vehicle is being driven. In one particular example, the method comprises temporarily reducing fuel cell power below a requested fuel cell power; supplementing the fuel cell power reduction with battery power; and performing the anode leak test during the temporarily reduced fuel cell power. Moreover, by using an alternative energy source to supplement the fuel cell power, the leak detection method can be triggered based on one or more operating conditions like a driving profile, a state of system control, a temperature, and/or an engine load (e.g., a vehicle speed). In this way, the technical result can be achieved that conductance of the anode leak test may be performed more frequently and during vehicle operation, for example, while the vehicle driving in motion on the road.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings. It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.